The present invention relates to a two-phase dispenser device, i.e. to a dispenser that makes it possible to dispense a fluid and a gas (in general, air) simultaneously. This type of dispenser device is generally mounted on a reservoir containing the fluid to be dispensed. Such a device can be used for two different uses: in a first use, this type of dispenser is used as a foam pump making it possible to dispense fluid in the form of foam, i.e. mixed with fine air bubbles. In a second use, the device can be used to dispense the fluid in the form of a jet of finely-sprayed droplets entrained by the flow of air. In either use, the dispenser device is of identical design, incorporating a fluid pump and an air pump. A difference between the two uses lies in the proportions of air and of fluid. When such a device is used to generate a foam, it is necessary to have a proportion of air that is large compared with the proportion of air necessary for the use in which the addition, when the dispenser is used as a foam pump, it further includes a foam-forming chamber, whereas when it is used as a spray, it is generally equipped with an outlet nozzle making it possible to disperse fluid in the form of fine droplets.
In this type of two-phase dispenser device, it is important for the fluid to be mixed with the air as homogeneously as possible so as to avoid dispensing the fluid chaotically. Such homogeneous mixing is foam pump.
It has been observed that the homogeneity of the mixture depends to a large extent on the volume in which the mixture is formed, and more precisely on the turbulence that can be generated in that volume. In most prior art dispenser devices, the air is mixed with the fluid at the outlet of the dispenser, or else at the outlet of the fluid pump, as in Document EP-0 511 894.
Another prior art document, namely Document WO 95/30490, describes a two-phase dispenser device in rod, the free piston further being mounted to slide in a pump body so as to define the pump chamber. The free piston co-operates with the actuating rod to define the top valve of the fluid pump and the top valve of the air pump, the fluid under pressure flows into an internal duct formed inside the actuating rod. In addition, at the outlet of the top valve of the air chamber, the pressurized air flows through a separate duct. The fluid duct and the air duct meet at a spray nozzle that makes it possible to dispense the fluid in the form of a jet of fine droplets. There too, the air and the fluid are mixed only in a very small volume defined by the very limited inside volume of the nozzle. It should be noted dispensing in the form of a spray, and not for dispensing in the form of a foam. Therefore, the homogeneity of the fluid and air mixture is not an objective that is particularly sought after, unlike when the dispenser is used as a foam pump.
Mention may also be made of Japanese Patent JP-09193953 which describes a pump in which the outlet valve of the fluid pump is formed at the bottom end of the actuating rod, while the air chamber (which does not actuating rod, in the vicinity of the pusher. The fluid is delivered into the actuating rod and is mixed with air only at the outlet of the rod.
Another pump described in Document EP-0 613 728 is provided with a fluid outlet valve situated at the top end of the actuating rod and with an air pump outlet valve that communicates with the top end of the actuating rod via an air passageway which extends around the actuating rod. There too, the fluid and the air are mixed only at the outlet of the actuating rod, so that the mixing volume is small.
An object of the present invention is thus to define a two-phase dispenser device, particularly but not exclusively a foam pump, in which the fluid and the air are mixed in a large volume, making it possible for the mixture to have good homogeneity.
To this end, the present invention provides a fluid dispenser device comprising:
a fluid pump comprising:
a pump body provided with an inlet valve member;
an actuating rod mounted to move axially in the body; and
a free piston mounted to slide in leaktight manner in the body, said piston being mounted to move over the actuating rod to form an outlet valve member therewith; and
an air pump comprising an air chamber provided with an inlet valve member, with an outlet valve member, and with a piston for compressing the air in the chamber;
the outlet valve of the fluid pump and the outlet valve of the air pump opening out into a common duct.
Thus, by causing the two pump chambers to open out into a common duct, the fluid and the air are mixed as early as possible, so that the mixing takes place in a volume that is larger than when the air is mixed with the fluid only at the outlet of the dispenser device. Also, the path along which the fluid and the air flow together is very long and sinuous, which contributes to forming turbulence that is necessary for foam of good quality.
Advantageously, the outlet valve of the air pump is formed by the free piston. Therefore, a single part performs the two functions of moving member and of outlet valve. In addition, the actuating rod forms a valve seat for the outlet valve of the air pump. Thus, the free piston firstly makes it possible to isolate the two chambers from each other, and secondly forms the moving valve member for the outlet valves of both chambers.
In order to increase the volume in which the fluid and the air mix, at the free piston the actuating rod defines a plurality of radial channels surrounded by an inside wall of the free piston, together defining a portion of said common duct. It is thus possible for that portion of the actuating rod which is situated at the free piston to be formed such that it has a cross-section substantially in the shape of a three-, four-, or five-pointed star, depending on the number of radial channels that are to be formed. The sum of the cross-sectional areas of the various radial channels is considerably larger than the cross-sectional area of a conventional internal channel extending inside the actuating rod. Therefore, the geometrical shape of the mixing volume is very complex and, as a result, it generates considerable turbulence. In addition, since the common duct has a large cross-sectional area, there is only a very small amount of head loss at the outlets of the valves, which makes it possible for the dispenser device to be particularly easy and smooth to actuate.
In one embodiment, the free piston is provided with at least one sealing lip in leaktight sliding contact with the body, and is provided with a sealing lip in leaktight sliding contact with the actuating rod. In addition, the actuating rod includes a bushing that defines an inside sliding wall against which the sealing lip is in leaktight sliding contact. It is advantageous for the piston to penetrate into the bushing with its sealing lip: in this way, the sealing lip is pressed strongly against the inside sliding wall by the fluid under pressure that flows through the common duct at the outlet of the valve. It is thus possible to avoid any risk of leakage where the lip of the piston is in sliding contact in the bushing of the rod.
In order to open the top outlet valve of the air pump, the inside sliding wall of the bushing is provided with at least one seal-breaking profile at which the sealing lip of the piston is no longer in leaktight contact, so as to form an air passageway through which air can pass to the common duct. In one embodiment, the seal-breaking profile is in the form of a recess or of a cut provided in the inside wall of the bushing. In a variant, the seal-breaking profile is in the form of a flat that interrupts the roundness in the inside wall of the bushing.
When such a dispenser device is used as a foam pump, the common duct communicates downstream with a foam-forming chamber. When the dispenser device is used as a spray, the common duct communicates downstream with an outlet spray nozzle.